Updates to this story
A team has come up with a new touchscreen display that doesn't require rare and expensive raw materials such as indium.
Indium-tin-oxide (ITO) is normally used for the wafer-thin electrode under the glass surface of a touchscreen display - it's excellent at conducting slight currents and lets the colours of the display show through clearly.
Unfortunately, the stuff is in very short supply, making a readily-available alternative something of a holy grail for the industry. The US Geological Survey reckons that the world supply will be exhausted by 2020 at the latest.
But the Fraunhofer team says it's found an alternative that's just as good - and vastly cheaper. Its main components are carbon nanotubes and low-cost polymers.
The electrode foil is composed of two layers. One is the carrier, a thin foil made of polyethylenterephthalate PET, the same cheap plastic used for making bottles. Then a mixture of carbon-nanotubes and electrically conducting polymers is added, forming a thin film as it dries.
This combination by itself isn't particularly durable, because humidity, pressure or UV light put a strain on the polymers. But the carbon nanotubes harden on the PET to anchor the electrically conducting polymers.
""he electrical resistance of our layer is somewhat greater than that of the ITO," says project manager Ivica Kolaric. "But it’s easily enough for an application in electrical systems."
Kolaric says there are many other applications for the foil, including photovoltaic foils that could line corrugated roofs or other uneven structures.
Indium-containing raw materials exist abundantly. The metals industry has been investing in process improvements and capacity over the last several years to bring more indium to the market. This industry can and will continue to do so if the demand is there. Short-term availability issues always exist intermittently (for many materials, including indium), due to numerous factors including the time lag required to install additional capacity, government regulation, & the lack of information suppliers receive about future demand.
Based on mining reserves (100 years at a rate of 500 MT of virgin indium per year), plus residue reserves (30 years at a rate of 500 MT per year), combined with continued improvements in recoveries of virgin and reclaimed materials, and on-going exploration, the indium supply is secure.
More on indium sustainability can be found in 2 papers, one published by the Indium Corporation, the other one published by the United States Geological Survey:
1) http://bit.ly/94VNVp
2) http://pubs.usgs.gov/of/2004/1300/2004-1300.pdf
We are available for any further explanation needed.
Rick Short
www.indium.com
I realize it is "PC" to evangelize the scarcity of rare earth metals and that Carbon nano-tubes are the sexy new thing. However, all you are really doing is enabling China to increase the price of these commodities and overstating the advantages of Carbon nano-tubes. It would be more responsible of you to present the challenges of Carbon nano-tubes in this application a little more clearly. As you stated in the article this nano-tube impregnated polymer has a higher resistance than the indium film meaning higher power requirements. Since it is a mobile application a replacement for the Indium film must be superior in all characteristics before it will be commercially viable.
The USGS article they link to says there is 5,700 t of Indium left. Rick/Emily claims that they can produce 100 years of 500 t/year. How?
Or are they worried because we might transition off Indium to carbon nanotubes and they won't be able to charge several hundred $ per kg?
Which do you think?